Conventional firearm mechanisms are mechanical, relying on a combination of a lever, spring, and sear to transform pressure applied to the trigger lever to a release of the firing pin. The firing pin used in firearms usually has a small, rounded portion designed to strike the primer of a cartridge, detonating the priming compound, which then ignites the propellant (inside) or fires the detonator and booster. Firearms use triggers to initiate the firing of a cartridge in the firing chamber of a weapon. This is typically accomplished by actuating a striking device through a combination of spring and kinetic energy causing the firing pin to strike and ignite the primer of the cartridge. Firing is the sequence of events which ignites the propellant charge in the cartridge. The cartridge primer contains a small amount of percussion-sensitive explosive. When a striker hits the primer with sufficient mechanical pressure it detonates the primer material. This sends hot burning particles of primer material into contact with the propellant, initiating its burning. In single-shot and semiautomatic operation, each activation of the trigger results in only one shot being fired. In a fully-automatic operation, the entire operating cycle repeats itself as long as the trigger is pulled and ammunition is fed.
There are many ways to organize the mechanical firing chain. Probably the most common striker is a slender steel rod called a firing pin. In most cases, the firing pin is struck at the rear by a rotary hammer. Energized by the hammer, the firing pin then strikes the primer. In other designs, the firing pin is propelled directly by its own spring, or the hammer impacts the primer directly without an intervening firing pin. In modern revolvers the hammer usually hits a transfer bar which is moved into position only when the trigger is pulled. With the transfer bar in proper position, the striker can hit the transfer bar which then hits the primer. When the transfer bar is out of position, the gun should not discharge inadvertently if the gun is dropped.
There are two primary types of striking mechanisms: mechanical based hammers and strikers. Hammers are basically spring-tensioned masses of metal that pivot on a firing pin when released and strike the firing pin to discharge a cartridge. Strikers are essentially spring-loaded firing pins that travel on an axis in-line with the cartridge eliminating the need for a separate hammer, as discussed above. The hammer of a firearm is a part propelled to impart a blow (impact) that will initiate the weapon firing when the trigger is pulled. Its name comes from its resemblance and functional similarity to the common hand tool of the same name. The proximal result of the hammer's blow depends on the mechanism of the lock or action of which it forms a part.
Some weapons have been designed to fire electrically primed ammunition. Most of these require batteries carried in the gun, while some others have been designed with very complicated electromagnetic devices to generate the charge necessary to fire ammunition. A simple, reliable electromechanical firing mechanism containing a foolproof and fail-proof source of voltage would be accepted by most shooters and would make electric guns and ammunition popular. Such a firing mechanism could be more reliable than the current guns using mechanical strikers due to the greatly reduced number of parts, shortening of firing times, enabling electronic fire control using existing ammunition, and the reduction of the risk of slam fire.